Production of olefins



Patented Feb. 20, 1951 PRODUCTION OF OLEFIN S James A. Dlnwiddie, Goose Creek, Tcx., assignor,

by mcsne assignments, to Standard Oil Development Company, Elizabeth, NHL, a corporation of Delaware Application October 17,1947, Serial No. 780,388

4 Claims. (01. 260-482) '1 The present invention is directed to a method for producing olefinic hydrocarbons. ticularly, the invention is directed to a method whereby oxygenated organic compounds are converted to oleflnic hydrocarbons.

Oleflnic hydrocarbons do not occur naturally I 'in large quantities. However, they are produced in appreciable quantities in the cracking of petroleum. Thus, since the advent of cracking petroleum hydrocarbons on a commercial scale (circa 1912), olefinic hydrocarbons have been available inincreasingly large quantities. These materials are valuable starting points in the synthesis of a number of valuable olefinic derivatives.

Natural petroleum is being consumed at increasingly high rates throughout the world. Consequently, searches for crude petroleum are being extended to a marked degree. The high consumption of crude petroleum has'caused some concern with regard to the depletion of these natural resources. Therefore, the refiner of crude petroleum has turned his attention to methods of producing synthetic petroleum. These methods for producing synthetic products usually include the classic work of Fischer and Tropsch in which carbon monoxide and hydrogen are reacted in the presence of a catalyst to form a mixture of hydrocarbons and oxygenated organic compounds. The hydrocarbons are quite useful when separated from the oxygenated organic compounds and the same applies to the organic organic compounds to other more valuable materials may achieve considerable importance.

I have now discovered a method for converting oxygenated organic compounds, such as the glycols and oxides of the mono-oleiins, to the olefinic hydrocarbons. It has been found that the olefin glycols. such as the homologous series beginning with ethylene glycol and the olefin oxides, which are illustrated by ethylene oxide, and its homologues, may be converted in substantial yields to the corresponding olefins by passing the heated glycol or oxide in a vaporized condition over a catalyst comprising a metal or oxide of the iron type elements of Group VIII of the periodic table in admixture with a suitable alkaline promoting material.

The present invention may be described briefly as involving the vaporization of an oxide or glycol More par-' of the type mentioned, heating the vaporized material to a temperature in the range from about 400 to 1000 F., and contacting the heated vaporized oxygenated compound with a catalyst, maintained at the aforementioned temperature, such as that illustrated by the iron oxides, suitably promoted with an alkaline material, such as potassium carbonate, to form a product including an appreciable quantity of the monoolefin.

The type of catalysts employed in the present invention will usually be iron, cobalt, and nickel, either as the metals themselves or the oxides thereof, or mixtures of the oxides of the metals. For example, F6203 is a suitable catalyst in the practice of the present invention.

The catalyst should be promoted with a material such as illustrated by potassium carbonate, potassium chloride, potassium fiuoride, the corresponding compounds of lithium and sodium, magnesium oxide, copper oxide, and other similar promoting materials which have been found suitable in promoting the activity of the catalysts of the Group VIII metals.

The promoter, as exemplified by potassium carbonate, will usually be employed in the catalyst in relatively small amounts. For example, an amonut of promoter in the range from about 0.5 to about 15% will usually sufiice with a preferred range of about 1 to about 8%.

The temperature of the reaction in which the glycols and oxides are converted to the monoolefins may range from 400 to about 1000 F. with a preferred temperature in the range from about 450 to 650 F.

Pressures may range from about atmospheric pressure up to about 500 pounds of pressure with a preferred range of from about 50 pounds to 300 pounds per square inch gauge.

The feed, including the glycol or the oxide, may be contacted with the catalyst for a time surficient to give a feed throughput corresponding to about0.1 to about 1 volume of feed per 1 volume of catalyst per hour. Some leeway in this respect is allowed; for purposes of obtaining higher conversions, it may be desirable to employ a low throughput whereas, when the unreacted materials are recycled, high throughputs may be desirable. Thus, it may be possible to increase the throughput up to about 3 volumes of feed stock per volume of catalyst per hour.

The process of the present invention may be conducted either by contacting the oxide or the glycol with the catalyst in a fixed bed operation in which the catalyst is arranged in cases or a "i i' undercircumstances where heat consumption is large since the dispersion of the finely divided catalyst in the vaporized feed allows a ready dispersion of the heat which may be generated by the reaction.

The invention will now be further illustrated by reference to the drawing in which the sole figure presents a flow diagram of one mode of practicing the invention.

Referring now to the drawing, numeral ll designates a feed line through which aglycol, such as ethylene glycol, or an oxide, such as ethylene oxide, may be introduced into the system. Assuming that the feed stock is ethylene glycol, it is passed through line H into a furnace i2 in which is located a heating coil 13. Furnace I2 is provided with a burner I! wherein the temperature of the feed in heating coil I3 is raised to a temperature in the range between about 400 and 1000 F. The vaporized and heated feed then discharges from furnace 12 by line I! into a reactor 16 containing a catalyst bed I I. For purposes of illustration, it is assumed that catalyst bed I I is comprised of iron oxide containing approximately 3 by weight of potassium carbonate. The heated ethylene glycol passes through catalyst bed I! and is converted on contact therewith to a product including a substantial amount of the mono-olefin, ethylene.

The product issues from reaction zone ili by way of line It containing a cooler 19 which reduces its temperature to substantially atmospheric temperature before it discharges into separator 20. In separator 20, a separation is made between fixed gases, including the oxides of carbon as well as hydrogen, which are removed from the separator by line 2| for further use as may be desired, and a liquid phase including hydrocarbons, unreacted feed stock, and water which is discharged by line 22. Line 22 introduces liquid product into a distillation zone 23. Distillation zone 23 is shown as a single distillation tower equipped with a heating means, such as a heating coil 24, for adjustment of temperatures and pressures. It will be understood, of course, that distillation zone 23 may include a plurality of distillation towers, but, for purposes of simplifying the description, distillation zone 23 is shown as a single distillation tower. Itwill be further understood that distillation zone 23 will be provided with suitable internal equipment, such as bell caps, plates, and the like, to insure intimate contact between liquids and vapors.

Conditions of temperature and pressure are adjusted in distillation zone 23 to obtain overhead by line 25 an oleilnic fraction including ethylene, a water fraction by line 28 which may contain dissolved oxygenated organic compounds, and an unreacted ethylene glycol fraction by V 4 tion provides a simple effective process for pro ducing oleiins from oleilnic glycols and the oleflnic oxides.

While not described in the description taken with the drawing, it may be desirable under some conditions to dilute the feed with a diluent, such as a light hydrocarbon as illustrated by methane, or with a substantially inert gassuch as nitrogen, waterv vapor, and the like. It may also be desirable to include in the feed stock an oxide of carbon which may be removed with the gases vented by line 2i.

The invention will be further illustrated by specific runs in which ethylene glycol, in one instance, was contacted with a catalyst comprising Feaor and containing 3% by weight of potassium carbonate. The ethylene glycol was heated and vaporized and passed at a temperature of 575' F. and at a pressure of 150 pounds per square inch gauge over the catalyst ata-feed rate of 0.3

volume of feed per volume of catalyst per hour.

' other gases including hydrogen, carbon monoxide and carbon dioxide. Some water was also formed. In another run, propylene glycol was passed, under comparable conditions, over the same catalyst and the product was found to contain propylene.

In a third run, propylene oxide was charged to the system and passed over the catalyst under comparable conditions to obtain a product which was found to contain 35.6% by volume of propylene.

From the foregoing runs, it may be seen that a product including substantial yields of monoolefins may be produced irom either ethylene glycol, propylene glycol, or propylene oxide.

It is not understood just exactly what reactions are involved in the production of mono-oleilns from the glycols and the oxides since ordinarily one would expect the glycols to dehydrateto the aldehydes'. according to the well-known equations illustrated in the various organic chemistry texts. Therefore, the mechanism by which the oxides and glycols are converted to olefins is not understood. It is postulated, however, as a partial explanation, which is given for a better understanding of the invention and not for limitation thereof, that a dehydration and a hydrogenation reaction may be involved. When a glycol or oxide containing four or more carbon atoms is processed in accordance with the present invention, one would expect that if a simple dehydration was the explanation that the diolefln rather than the mono-olefin would be produced. The fact that water is obtained indicates that a portion of the reaction mayinvolve dehydration of the'glycols and oxides.

While theinvention has been described and illustrated by examples in which the catalyst was contacted with ethylene glycol, propylene glycol,

' and propylene oxide, it is to be understood that line 21 which may be routed thereby to the feed other glycols and oxides may be employed. For

example, the higher members of the same homologous series to which ethyleneand propylene glycols belong may housed in lieu of these materials. Similarly, the higher olefin'ic oxides may be used as feed stock in the process. As exemplary of the higher members of the two series of compounds which may be found useful in the present invention may be mentioned the butyiene glycols, the pentylene glycols, and other higher molecular weight members of the series. Similarly, ethylene oxide, butylene oxides, pentylene oxides, and other higher molecular weight monoolefin oxides may be used in lieu of the ones illustrated in the examples.

This application contains subject matter common to the subject matter claimsd in Serial No.

780,387. The common subject matter of this application and Serial No. 780,387 is the treatment of mono-olefin oxides at an elevated temperature with the catalyst employed in the present invention to obtain a mono-olefin having the same number of carbon atoms as the mono-olefin oxide.

The nature and objects of the present invention having been fully described and illustrated, what I wish to claim as newand useful and to secure by Letters Patent is:

1. A method for producing olefins which comprises the steps of contacting a mono-olefin glycol with a catalyst selected from the Group VIII metals and oxides thereof containing an alkaline promotor for the reaction in an amount in the range between 0.5% and 15% by weight at a temperature in the range between 400 and 1000 F. to produce a product including a mono-olefin having the same number of carbon atoms as the mono-olefin glycol and recovering said monoolefin.

2. A method for producing a mono-olefin which comprises the steps of vaporizing a mono-olefin glycol having at least two carbon atoms, heating said mono-olefin glycolto a temperature in the range between 400 and 1000 F., contacting said heated, vaporized mono-olefin glycol with a metal selected from the metals and oxides thereof of the Group VIII metals and including an alkaline promoter for the reaction in an amount in the range between 1% and 8% by weight at a temperature in the range between 400 and 1000 F. and a pressure in therange from atmospheric to 500 pounds per square inch gauge for a time sufiicient to form a product including a mono-olefin having at least two carbon atoms and the same number 01' carbon atoms as the monoolefin glycol and recovering from said product said mono-olefin.

3. A method for producing ethylene which comprises the steps of vaporizing ethylene glycol, heating the vaporized ethylene glycol to a temperature of approximately 575 F., contacting the heated vaporized ethylene glycol with iron oxide containing approximately 3% by weight potassium carbonate at a temperature of 575 F. and at a pressure of pounds per square inch gauge under conditions to form a product including ethylene and recovering ethylene from said product.

4. A method for producing propylene which comprises the steps of vaporizing propylene glycol, heating the vaporized propylene glycol to a temperature of approximately 575 F., contacting the heated vaporized propylene glycol with iron oxide containing approximately 3% by weight potassium carbonate at a temperature of 575 F. and at a pressure of 150 pounds per square inch gauge under conditions to form a product including propylene and recovering propylene from said product.

JAMES A. DINWIDDIE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A METHOD FOR PRODUCING OLEFINS WHICH COMPRISES THE STEPS OF CONTACTING A MONO-OLEFIN GLYCOL WITH A CATALYST SELECTED FROM THE GROP VIII METALS AND OXIDES THEREOF CONTAINING AN ALKALINE PROMOTOR FOR THE REACTION IN AN AMOUNT IN THE RANGE BETWEEN 0.5% AND 15% BY WEIGHT AT A TEMPERATURE IN THE RANGE BETWEEN 400* AND 1000* F. TO PRODUCE A PRODUCT INCLUDING A MONO-OLEFIN HAVING A SAME NUMBER OF CARBON ATOMS AS THE 